Established manufacturers who have teased electric motorcycles in the past have had a quiet year. While Harley Davidson and Yamaha have both shown working concepts, neither has moved into building them yet.

Another challenge is that electric motorcycles continue to cost more than their gasoline-powered counterparts. This is starting to be offset by increasing availability of used electric motorcycles, making the entry point more accessible.

Deals are also available: over the past year, Victory has offered $10,000 customer cash, whle Energica gave a generous trade-in allowance plus $6,600 back if you purchased an Ego or Eva. So the price of an electric motorcycle continues to fall from its level a year ago.

The Zero SR has improved for 2017 in some incremental but important ways. A higher-power controller pumps up the torque to 116 ft-lbs for acceleration in hard driving, new paint gives a more refined look, and a wider drive belt makes for more confident and spirited riding.

The mobile app has been improved to allow riders to download updates to the software via WiFi, reducing the need for dealer visits. And a locking tank-trunk makes the onboard storage space more secure.

The 16.3-kwh battery pack includes a 3.3-kwh charge tank, upgraded from last year's 2.8 kwh. If the range already meets the needs of the rider, an alternative charge tank is available to add 2.5 kw of charging capacity for $1,995.

That charge tank boosts the bike's total charging rate to 3.8 kw, cutting charge times significantly. A Bosch ABS system paired with J-Juan brakes, Showa suspension, and Pirelli Diablo Rosso II tires completes the package, making this year's SR far more refined than its predecessor two years ago.